Gun control laws have been in a considerable state of flux for many years. Although in Illinois you are allowed to exercise your second amendment right to possess a firearm for self-defense, many still get in tangles with the law (see here for details on what warrants a charge of an unlawful use of a firearm or here for details regarding more serious affairs).
There are many reasons for this, but an undoubted central source would have to be the many changes to the laws governing guns over the years. More specifically, the last couple of decades have seen significant changes. The following are sections of significant change within the last 20 years of gun law history.